Add the ability to tweak RENOVATE_PERSIST_REPO_DATA (or new variable) to only store .git folder

[jamietanna]

What would you like Renovate to be able to do?

When using RENOVATE_PERSIST_REPO_DATA on ~20 few repos with Bundler and NPM installed, this leads to ~2GB repo cache.

Being able to tweak this to just cache the .git folder would significantly reduce the cache size, while still containing benefit to reduce the git fetch time in the future.

If you have any ideas on how this should be implemented, please tell us here.

Allow RENOVATE_PERSIST_REPO_DATA=git or a new environment variable RENOVATE_PERSIST_GIT_DATA=true

Is this a feature you are interested in implementing yourself?

Maybe

[jamietanna]

Actually it may be possible by caching + restoring the --base-dir

[rarkins]

We'd need to know the exact commands you think would be required